1. Field of the Invention
The field of the invention is that of subscription television and radio.
More precisely, the invention concerns a device for assisting a user having purchased fees entitling him to have access to television and radio programs.
2. Description of the Prior Art
There are many known subscription television systems in which the programs are transmitted in scrambled form. The user selects those items of a program that he wishes to view and pays the corresponding fees. These fees correspond, for example, to the acquisition of a particular key for the descrambling of the programs received.
A subscription television system such as this provides the facility of advance buying, namely the payment of fees, for example in the form of a monthly subscription, enabling him to view an item of a program. It may also enable impulse buying giving the user the possibility of paying a fee to view an item of a program only when it is broadcast.
The systems for controlling access to television programs, notably the system described in the "Eurocrypt" specifications, implement a security processor, notably in the form of a microprocessor card. In addition to a certain number of mechanisms related to the reliability of the system in terms of inviolability, a certain number of elements are defined in these processors: these are elements representing the facilities for marketing audiovisual products.
Thus, the "Eurocrypt" specifications provide for possibilities of selective access to certain subjects (sports, theater etc.), for groups of users (doctors, garage mechanics etc.), for certain periods etc.
The management of an access control service is done notably through values of identifiers and flags or indicators. These elements are found, in the same form, in the safety processor of the user's decoder. It is then difficult to consult the user's account status recorded in this processor.
If necessary, the user may display certain pieces of information contained in the processor. However, these pieces of information cannot be directly interpreted since they are in digital form. The interpretation calls for transcoding tables which can be consulted, for example, through a Teletel type information-retrieval center, outside the context of use of the security processor, or in a center qualified to fulfil this function.
Furthermore, existing subscription television services do not give the user any indication of management as regards the possibilities offered by those providing programs. The information presented is not enough for to let the user choose and acquire an item of a program, whether it is in advance or on impulse.
The European patent document 0 243 312 (Method To Facilitate Dialogue Between A Subscriber To A Subscription Television System And A Decoder Of The Signals Received, And A Decoder Of These Signals) concerns a method for the transmission of information on television programs and the modalities of subscribing to them in teletext form. However, the information transmitted is common to all the users and is not related to the information contained in the security processor of a particular user. Thus, for example, it is not possible to transmit specific information to the group of users who are doctors, or to a user having a particular type of basic subscription.
It is an aim of the invention, notably, to overcome these drawbacks.